(a) Technical Field
The present invention relates to a method for controlling a fuel cell vehicle, in which a torque correction factor is used for protecting fuel cell, reducing start-up time and improving driving performance.
(b) Background Art
In a conventional fuel cell-battery hybrid vehicle, a high-voltage DC-DC converter is positioned between a fuel cell and a battery to absorb a voltage difference between the fuel cell and the battery and performs a charge-discharge control of the battery or a power control of the fuel cell. Accordingly, it is not necessary to provide a strategy for a specialized start-up control to match the voltages of the fuel cell and the battery.
On the other hand, in a fuel cell-battery hybrid vehicle that does not employ any high-voltage DC-DC converter, an initial battery charging device and a start-up control strategy corresponding to the same are required to match the voltages of the fuel cell and the battery.
U.S. Pat. No. 6,815,100 discloses a control device for starting a fuel cell which prevents an excessive reduction of the fuel cell by controlling an output current of the fuel cell using a DC-DC chopper provided at the output side of the fuel cell, before the fuel cell is connected to a power storage unit with a reduced voltage, after the power storage unit such as a battery supplies electric power to a motor and auxiliary devices for driving the fuel cell during start-up of the vehicle.
Moreover, Korean Unexamined Patent Application Publication No. 2006-0003543 discloses a method of controlling start-up of a fuel cell-supercapacitor hybrid vehicle, in which, during start-up, a fuel cell is started by an auxiliary battery, electric power of the fuel cell is charged in a supercapacitor through a multi-resistor of an initial supercapacitor charging device and, when the voltage of the supercapacitor becomes equal to that of the fuel cell, the fuel cell is connected to the supercapacitor by a main relay so that the vehicle may be driven.
However, the above conventional start-up control methods have a drawback in that the DC-DC converter or the initial charging device with a multi-resistor is required to charge the power storage unit or the supercapacitor. Moreover, when a fuel cell only mode is changed to a hybrid mode, where the fuel cell and the supercapacitor are directly connected, torque may be suddenly increased by depression of an accelerator pedal, and thus the vehicle may move suddenly.
Accordingly, an appropriate start-up sequence control, which can protect the fuel cell, reduce the start-up time, charge the supercapacitor, and improve the driving performance at the same time, is required in the fuel cell-supercapacitor hybrid system.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.